2. To make sashes, cut each sleeve open along seam. Fold each in half lengthwise and cut at crease to create two equal pieces. You should have four total.
3. Glue two pieces of sleeve fabric together at hemmed ends, overlapping one on top of other about 1”. Join remaining two pieces in same way.
4. Lay one sash on ironing board, wrong side up. Turn one long edge of strip under (toward wrong side) ¼” and glue in place. Repeat for other long edge, and one short edge. Fold sash in half lengthwise, right side out, and press. Make sure that folded sash is the same width all the way down. Glue hemmed edges together, leaving one short edge raw. Repeat for other sash.
5. To attach sash to shirt, line up closed end of one sash with shoulder seam and glue in place so sash falls to front of shirt. Repeat with other sash.
6. Cut raw ends of sashes at a 45-degree angle. Turn edges under ¼” and glue.
7. Reinforce as needed with a simple hand stitch.